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6.
Active Solar Power
Energy from sun is
stored in a “thermal
mass”
When needed, heat
from thermal mass is
then pumped
throughout structure

7.
Active Solar Power
 This also refers to
electrical generation
using solar power
 Two ways to do this are
photovoltaic cells and
huge commercial
electric facilities
 This shows the diagram
for the house seen in the
previous slide. The PV
panels are on the roof

9.
Large-scale Solar Electric Site
These facilities use solar power to heat
water to form steam. The steam goes to
generate electricity just as in fossil fuel or
nuclear electric plants.
No release of air pollutants
No electricity generated at night
They do work on cloudy days, though.

10.
Passive Solar Power
Works on the
principle that hot air
rises and cool air
sinks (convection)
Solar heats air and it
moves through
convection through
the structure or to
thermal mass

11.
Passive Solar Power
Mass wall or
“Trombe Wall
Using back wall as “mass”
To
rest
of
house

12.
Solar Power
Benefits
– Abundant
– No greenhouse gases,
few other pollutants
– Simple, minimal
repair needed
– Cheap over the long
term
 Detriments
– Retrofitting needed if
structure is not already
designed as passive solar
– Has limitations, night,
some locations better
such as south rather than
north facing slopes
– Initial capital outlay can
be high

14.
Wind Power
• Wind power is the conversion of wind
of wind energy into a useful form of energy.
• Most modern electrical wind power is
generated by converting the rotation of turbine
blades into electrical currents by means of
an electrical generator.
• Wind power is also used to propel ships
using sails.
• Windmills provide mechanical power, and
were originally developed for milling
grain for food production.

15.
Wind power
Can be used for mechanical tasks, e.g.
pumping water
Areas where winds are
stronger and more
constant, such as
offshore and high
altitude sites, are preferred
locations for wind farms.

16.
Electrical Power Windmills
High speed, low
torque machines
Will turn themselves
off if wind speed
exceeds their limits.
Used for generation of
electricity for direct
use or storage in
batteries

22.
• The power of flowing water has been used for
hundreds of years to operate machinery. This power
can also be used to generate electricity.
• Large scale hydroelectric schemes involve building
a dam across the end of a river valley to create a
reservoir.
• This is done high up in a mountainous area.
• Once they are built, hydroelectric schemes provide
a cheap and reliable source of electricity.
Hydro Power

26.
What Is Biomass Energy
• Biomass energy is the use of living and recently
dead biological material as an energy source.
• Ultimately dependent on the capture of solar energy
and conversion to a chemical (carbohydrate) fuel.
• Theoretically it is a carbon neutral and renewable
source of energy.

27.
How It Works
• Traditional: forest management, using wood as
fuel
• Use of biodegradable waste
Examples: manure, crop residue, sewage, municipal solid
waste
• Recent interest in agricultural production of
energy crops
 Should be high yield and low maintenance
 Examples: corn, sugarcane, switchgrass, hemp, willow,
palm oil, rapeseed, and many others
 Does not have to be a food crop
 Recent interest in bioengineered (GM) plants as fuel
sources
Production of a liquid or gaseous biofuel
Biogas due to the breakdown of biomass in the absence of O2

33.
How It Works
– Geothermal power plants
• Use earth’s heat to power steam turbines
– Geothermal direct use
• Use hot springs (etc) as heat source
– Geothermal heat pumps

34.
Advantages
• Renewable
• Easy to exploit in some cases
• CO2 production less than
with fossil fuels
• High net energy yield

35.
Disadvantages
Disadvantages
Not available everywhere
H2S pollution
Produces some water pollution
(somewhat similar to mining

36.
Conclusions
 Major difficulties in attaining target of
10% of electricity generated by
renewables by 2010
 Main contributors to this target will be :-
1)Offshore and Onshore
windfarms/clusters
2)Biomass/wood, straw, etc
3)Photovoltaic
 But policies like Climate Change Levy
and the Renewables Obligation will help
establish renewables.